It's interesting but disappointing that there's no standout "winner" among desktop GUI toolkits. Among other things, devs want to write software that runs on their favorite GNU/Linux distribution, but that also runs nicely and is easily installed on MS Windows and Mac OS X. Ideally there would be an API that abstracts over each platform's GUI toolkit, giving native look-and-feel from one code-base.
I came across this old thread on the topic: https://news.ycombinator.com/item?id=423119 and there didn't seem to be an agreed upon solution.
Have things improved in the last 3005 days?